<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>unicode编码表</title>
	<script type="text/javascript">

		while(true){
			var num1 = prompt("请输入小明的期末成绩");
			if(num1 >= 0  && num1 <= 100){
				break;
			}
			alert("请输入有效的分数！！");
		};
		 


			if(num1 == 100){
			alert("你满分");
		}else if(num1  >= 80){
			alert("优秀");
		}else if(num1  >=  60){
			alert("及格");
		}else{
			alert("差");
		}
	
		
		
		

	</script>
</head>
<body>

</body>
</html>